platform/sensinact-core/src/main/java/org/eclipse/sensinact/gateway/core/ResourceConfigCatalogCollection.java

/*
* Copyright (c) 2020 Kentyou.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
*    Kentyou - initial API and implementation
 */
package org.eclipse.sensinact.gateway.core;

import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;

/**
 * A collection of {@link ResourceConfigCatalog}s
 * 
 * @author <a href="mailto:christophe.munilla@cea.fr">Christophe Munilla</a>
 */
public class ResourceConfigCatalogCollection {
	Deque<ResourceConfigCatalog> catalogs;

	/**
	 * Constructor
	 */
	public ResourceConfigCatalogCollection() {
		this.catalogs = new LinkedList<ResourceConfigCatalog>();
	}

	/**
	 * Adds the {@link ResourceConfigCatalog} passed as parameter
	 * 
	 * @param catalog
	 *            the {@link ResourceConfigCatalog} to add
	 */
	public void add(ResourceConfigCatalog catalog) {
		if (catalog == null) {
			return;
		}
		synchronized (this.catalogs) {
			this.catalogs.add(catalog);
		}
	}

	/**
	 * Deletes the {@link ResourceConfigCatalog} passed as parameter
	 * 
	 * @param catalog
	 *            the {@link ResourceConfigCatalog} to delete
	 */
	public void delete(ResourceConfigCatalog catalog) {
		if (catalog == null) {
			return;
		}
		synchronized (this.catalogs) {
			this.catalogs.remove(catalog);
		}
	}

	/**
	 * Returns an {@link Iterator} over the list of {@link ResourceConfigCatalog}s
	 * handled by this ResourceConfigCatalogCollection
	 * 
	 * @return an {@link Iterator} over this ResourceConfigCatalogCollection's
	 *         {@link ResourceConfigCatalog}s list
	 */
	public Iterator<ResourceConfigCatalog> iterator() {
		final ResourceConfigCatalog[] catalogsArray;

		synchronized (this.catalogs) {
			catalogsArray = new ResourceConfigCatalog[this.catalogs.size()];
			this.catalogs.toArray(catalogsArray);
		}
		return new Iterator<ResourceConfigCatalog>() {
			int position = 0;

			/**
			 * @inheritDoc
			 *
			 * @see java.util.Iterator#hasNext()
			 */
			@Override
			public boolean hasNext() {
				return position < catalogsArray.length;
			}

			/**
			 * @inheritDoc
			 *
			 * @see java.util.Iterator#next()
			 */
			@Override
			public ResourceConfigCatalog next() {
				if (hasNext()) {
					return catalogsArray[position++];
				}
				return null;
			}

			/**
			 * @inheritDoc
			 *
			 * @see java.util.Iterator#remove()
			 */
			@Override
			public void remove() {
			}
		};
	}

	/**
	 * Retrieves and returns the previously registered {@link ResourceConfig}
	 * described by the {@link ResourceDescriptor} passed as parameter if it exists
	 * in this ResourceConfigCatalogCollection
	 * 
	 * @param descriptor
	 *            the {@link ResourceDescriptor} describing the
	 *            {@link ResourceConfig} to be returned
	 * 
	 * @return the previously registered {@link ResourceConfig} described by the
	 *         specified {@link ResourceDescriptor} if it exists ; returns null
	 *         otherwise
	 */
	public ResourceConfig getResourceConfig(ResourceDescriptor descriptor) {
		Iterator<ResourceConfigCatalog> iterator = this.iterator();

		ResourceConfig resourceConfig = null;

		while (iterator.hasNext()) {
			try {
				ResourceConfigCatalog catalog = iterator.next();
				if ((resourceConfig = catalog.getResourceConfig(descriptor)) != null) {
					break;
				}
			} catch (ClassCastException e) {
				continue;
			}
		}
		return resourceConfig;
	}
}